1. Field of the Invention
The present invention relates to a scanning endoscope apparatus that scans directional illuminating light to obtain an image of a subject, an image processing apparatus that processes the image obtained by the scanning endoscope apparatus, and a method of operation of the image processing apparatus.
2. Description of the Related Art
Conventionally, scanning endoscope apparatuses that apply illuminating light to a subject in such a manner that the illuminating light has directionality, and receive reflected light while scanning a direction of application of the illuminating light to obtain an image of the subject have been proposed.
For example, Japanese Patent Application Laid-Open Publication No. 2011-19706 describes a medical observation system including a medical probe that scans laser light to observe an object, a laser light source that supplies the laser light to the medical probe, determination means for determining whether or not the medical probe is in a predetermined state, and control means for controlling an amount of laser light outputted from the laser light source based on a result of the determination by the determination means. It is disclosed that such configuration enables the amount of laser light to be limited to a safe level in a situation in which the laser light may enter the eyes of a surgeon or the like.
Also, in a technique described in Japanese Patent Application Laid-Open Publication No. 9-248281, an endoscope spectral apparatus (3) is used in combination with an electronic endoscope apparatus (2). The electronic endoscope apparatus (2) includes an electronic endoscope (4) including image pickup means, observation light illumination means (5) for supplying illuminating light for observation to the electronic endoscope (4), and a signal processing section (6) that processes a signal from the image pickup means. The endoscope spectral apparatus (3) includes measurement light illumination means (9) for applying measurement light, spectral means for performing spectrometric measurement (10), a measurement probe (11) to be inserted into a channel in the electronic endoscope (4), and timing control means (12) for controlling an operation timing of the spectral means (10). The measurement probe (11) includes a fiber bundle for illumination and a fiber bundle for light reception, and the fiber bundle for illumination is connected to the measurement light illumination means (9) and the fiber bundle for light reception is connected to the spectral means (10), respectively. Measurement light from the measurement light illumination means (9) is guided by the fiber bundle for illumination and applied to the inside of a living body (30). Light reflected from the inside of the living body (30) is received by the fiber bundle for light reception and guided to the spectral means (10). A signal synchronized with light blocking periods in which observation light is blocked is inputted to the timing control means (12) from the electronic endoscope apparatus (2). Then, the timing control means (12) makes the spectral means (10) perform spectral measurement, based on a measurement control signal synchronized with the light blocking periods. Consequently, it is disclosed that highly-accurate spectral measurement data that is not affected by observation light can be obtained with almost no change in specifications of the endoscope apparatus (2).
Such scanning endoscope apparatus is configured so that a direction of an output end of an optical fiber that guides illuminating light can be varied, and the direction of the output end of the optical fiber is varied as time passes, whereby illuminating light is scanned. On the other hand, a configuration that receives light from a subject is made so that, for example, all of light from within an illuminating light scanning range can be received.
Accordingly, information indicating from which direction received light has come (that is, from which part of a subject the received light has come) is not contained in a signal generated by the received light. Therefore, an endoscopic image is formed assuming that the received light is return light from a part of the subject to which the output light is applied.
With the above-mentioned configuration of the conventional scanning endoscope apparatus, an image of a subject can accurately be formed if there is no light other than return light from the subject within the light reception range; however, if there is extrinsic light other than return light (light that is not return light of illuminating light outputted from the optical fiber, for example, light generated by a treatment instrument for performing treatment of a subject, the treatment being accompanied by light emission, such as an electrosurgical knife or a therapeutic laser), detected light contains the extrinsic light. In other words, detected light is a sum of the return light from the subject to which the illuminating light has been applied and the extrinsic light received regardless of in which direction the illuminating light is applied.